1. Field of the Invention
The invention relates to vehicle axle/suspension systems, and in particular to the suspension assemblies of those systems which are useful for heavy-duty vehicles such as trucks and tractor-trailers. More particularly, the invention is directed to a heavy-duty trailing or leading arm rigid beam-type suspension assembly for trucks and tractor-trailers, in which the axle is securely and efficiently captured by the beams and an improved connector which is formed generally in the shape of the covered portion of a covered wagon. This connector structure, together with the manner in which the structure is placed on or attached to the axle and the beam, results in a lightweight, economical, sturdy and rigid axle-to-beam connection that eliminates U-bolts, U-bolt brackets/axle seats and associated hardware typically used in many prior art axle-to-beam connection designs, provides a more robust axle-to-beam connection and allows for greater flexibility in S-cam orientation over prior art U-bolt axle-to-beam connection designs.
2. Background Art
The use of air-ride trailing and leading arm rigid beam-type axle/suspension systems has been very popular in the heavy-duty truck and tractor-trailer industry for many years. Air-ride trailing and leading arm spring beam-type axle/suspension systems also are often used in the industry. Although such axle/suspension systems can be found in widely varying structural forms, in general their structure is similar in that each system typically includes a pair of suspension assemblies. In some heavy-duty vehicles, the suspension assemblies are connected directly to the primary frame of the vehicle. In other heavy-duty vehicles, the primary frame of the vehicle supports a sub frame, and the suspension assemblies connect directly to the subframe. For those heavy-duty vehicles that support a subframe, the subframe can be non-moveable or moveable, the latter being commonly referred to as a slider box, slider subframe, slider undercarriage, or secondary slider frame. For the purpose of convenience and clarity, reference herein will be made to a slider, with the understanding that such reference is by way of example, and that the present invention applies to heavy-duty vehicle axle/suspension systems suspended from primary frames, moveable subframes, and non-movable subframes.
Specifically, each suspension assembly of an axle/suspension system, includes a longitudinally extending elongated beam. Each beam is located adjacent to and below a respective one of a pair of spaced-apart longitudinally extending main members of the slider. More specifically, each beam is pivotally connected at one of its ends to a hanger which in turn is attached to and depends from a respective one of the main members of the vehicle. An axle extends transversely between and typically is connected by some means to the beams of the pair of suspension assemblies at a selected location from about the mid-point of each beam to the end of the beam opposite from its pivotal connection end. The opposite end of each beam also is connected to a bellows air spring or its equivalent, which in turn is connected to a respective one of the frame main members. A brake assembly and shock absorber also are mounted on each of the beams and/or axle. A height control valve is mounted on the hanger and is operatively connected to the beam in order to maintain the ride height of the vehicle. The beam may extend rearwardly or frontwardly from the pivotal connection relative to the front of the vehicle, thus defining what are typically referred to as trailing arm or leading arm axle/suspension systems, respectively. However, for purposes of the description contained herein, it is understood that the term “trailing arm” will encompass beams which extend either rearwardly or frontwardly with respect to the front end of the vehicle.
The beam on which the axle is mounted is typically either a top-mount/overslung beam or a bottom-mount/underslung beam. An axle is mounted on the top of and is supported by the bottom-mount/underslung beam-type, with generally an upper portion of the axle being exposed. Welding alone typically is inadequate to maintain the integrity of the rigid axle-to-beam connection for underslung beams due to certain loads to which the axle-to-beam connection is subjected during vehicle operation. Therefore, underslung axle-to-beam mounts must be fortified in some manner to maintain the mount integrity and prevent separation of the axle from the beams. Such fortification usually includes additional mounting hardware such as U-bolts, U-bolt brackets/axle seats and the like, resulting in a secure axle-to-beam connection more capable of withstanding operational loads. However, such hardware usually adds unwanted cost, weight and maintenance to the axle/suspension system.
Conversely, an axle is mounted on the bottom of a top-mount/overslung beam, with generally a lower portion of the axle being exposed. The majority of axle/suspension systems in commercial use today that are generally free of significant additional axle mounting hardware utilize top mount beams because of packaging constraints. (The Assignee of the present application is the owner of at least two such patents: U.S. Pat. No. 5,366,237 and U.S. Pat. No. 6,508,482; which describe axle/suspension systems that are generally free of additional axle mounting hardware of the types described hereinabove, including, U-bolts, U-bolt brackets/axle seats and the like.) Many axle/suspension systems that use top-mount beams also augment the axle-to-beam weld mounts with additional mounting hardware, but again, sacrifice weight advantages as well as cost and maintenance efficiencies.
Therefore, a need exists in the art for an improved axle-to-beam connection for axle/suspension systems which utilizes a bracket or connector that replaces prior art U-bolts, U-bolt brackets/axle seats and the like, and which utilizes a new and improved method for attaching or placing the connector onto the axle and the beam in order to form the axle-to-beam connection. By replacing the mounting hardware, the improved axle-to-beam connection reduces weight and improves cost and maintenance efficiencies.